Design the world's most energy-efficient LED headlamps (on)

In December 2010, Nissan Motor Co., Ltd. launched the mass production electric vehicle "LEAF". The car uses the world's lowest power LED (light-emitting diode) headlamps. At least three LEDs are required for LED headlamps that have been used before. This time, the number of LEDs was reduced to two, and the power consumption was only 23W, which was reduced to about 1/3 of the previous halogen headlamps and about 2/3 of the LED headlamps.

In addition to energy saving, the design of the lamp is also very characteristic. Previous LED headlamps used light distribution with a projection lens and had a very similar appearance.

Figure 1: Project Manager of the P2P3 Project of the Research and Development Department of the City Light Industry Development Department

He has been responsible for this work since the beginning of the use of LEDs in automobiles, and has been the person in charge of the LED headlamp development project.

For the first time in the world, the new LED headlamps use a reflector (mirror) to distribute light. The original design is not visible in the appearance of the light source, and although it emits white light when it is lit, it looks blue when it is turned off.

Mosquito coil incident

The development of this headlamp is Shiguang Industrial, which is under the responsibility of a group of project managers from the Research and Development Department P2P3 project.

In reviewing the situation at the time, Murakami said, "I finally realized my dream. Although Shiguang Industrial started late in LED headlights, the practical application of new technology has made technicians full of sense of accomplishment."

The direct reason for the entry of the village bridge into the city's light industry was the invitation of a senior university student. But it is also because he likes cars and motorcycles. After graduating from the Department of Mechanical Engineering at the University of Science and Technology, he entered the work of the City Light Industry. "This is because I really like to make things, I am also very interested in the lights, I once raised the brightness of the motorcycle headlights."

After entering the company in 1988, the village bridge first internship in the factory to manufacture the combined lamp. "At the time, I felt that the size of the city's optical industry was great, both for workers and equipment." Later it was assigned to the Computer Aided Engineering (CAE) department. Mold design was carried out in the department, and product manufacturing was also involved in the workshop. In the second year, in 1989, he was transferred to the R&D department. At the beginning of his tenure, he received a task.

"This work is to find out how the dirt of the car lights is generated. Because the car lights installed in the roof of the car will be stained with dust or smoke oil, in order to find a countermeasure in this regard, we must first find out the reasons."

“Because I prefer to make things, I made my own car model, ignited 10 mosquito coils, analyzed the flow of smoke and the adhesion of soot and dirt. At that time, I was too focused, and the whole research and development building was smell of mosquito coils. There is no shortage of colleagues and seniors. This episode is still unforgettable."

According to the results of the mosquito-repellent incense experiment, the village bridge reported to the car manufacturer the cause of the dirt generated by the compartment lamp. At the same time, in addition to the flow path of the smoke, the influence of static electricity on the smoke oil was also considered, and a scheme for reducing the static electricity by replacing the material was proposed. .

Since then, the village bridge has been engaged in research and development of interior lighting. He also researched and developed lighting using new light sources, and was responsible for the development of a rear combination lamp and a High Mount Stop Lamp using a Neon Discharge Lamp. However, these products were not commercialized at the end.

Participate in the "Operation of Light" project

"Just like fluorescent lamps are gradually replaced by LEDs, xenon lamps have also been eliminated by the times. In addition, because of the need to set high-voltage circuits and take noise countermeasures, xenon lamps will increase costs, which is one of the obstacles to the commercialization of xenon lamps."

After that, Murakami participated in a large-scale research and development project called "Light Egg". The system developed is to mount a mirror around a HID (High Intensity Discharge), distribute light by optical fiber, and use it as a light source for each part of the car. This epoch-making idea is to use only one light source for a variety of lighting such as headlights, rear combination lights and interior lights.

“It also costs a lot of money. The reason is that the fiber is not as cost-effective as expected. Moreover, it is also necessary to use a visor and a filter of different colors depending on the application, which is also the bottleneck for developing the system. In addition, because there is only one light source, there is also the problem of how to carry out safety protection in the event of an accident. Although we actually made the system and implemented the driving experiment, it failed to reach the practical level.

However, by participating in a series of research and development work, the village bridge has gained an opportunity to contact the headlights. Murakami handled these projects in the second half of the 1990s, and LED technology made epoch-making progress during this period. Nichia Chemical Industry developed a blue LED in 1993. Then green LEDs were also developed, plus the already practical red LEDs, RGB three primary color LED products. In 1996, white LEDs using blue LED technology were also commercialized.

Figure 2: Headlights for Nissan's electric car "LEAF"

Nissan Motors used LED headlamps for the first time.

Figure 3: Headlight unit

The blue part is a low beam light using an LED. For the first time, the LED headlamps used a mirror method. It is characterized by a structure in which the light source is not visible from the outside. The low beam at the bottom is an ordinary halogen lamp.

“When I first entered the company, the industry generally believed that blue LEDs could not be realized, so its birth was shocking. At the same time, I also felt that 'lighting will change accordingly'”.

LED has long life, energy saving, low heat generation and high reliability.

"But the initial brightness is very low...and the cost is high."

The price of an original white LED is 10 times that of an incandescent bulb. To increase the brightness, multiple LEDs are required. To achieve the same brightness, the cost is 500 to 1000 times that of an incandescent bulb.

Red LEDs have been put into practical use in products such as high-position brake lights, and the practical use of white LEDs in the automotive field has been advanced from interior lights that do not require high brightness. City Light Industrial's LED interior lights were first applied to Nissan's "Cedric" and "Glory" door glass side lights (1998), and later promoted to Toyota "Alphard" "Indirect lighting (2002), and Nissan "TIIDA" map lights (2004) and so on.